The majority of women who quit smoking during pregnancy will relapse during the first year postpartum, and postpartum smoking has deleterious effects on the health of both the mother and her children. For example, smoking increases the risk of certain cancers, respiratory symptoms and reproductive complications among women, and exposure to tobacco smoke has been linked to sudden infant death syndrome, ear infections, respiratory illness and asthma among children. Previous interventions designed to address postpartum smoking have not successfully increased rates of sustained abstinence postpartum. However, our research has documented that mood and weight concerns are associated with postpartum smoking relapse, and pilot data support the acceptability of strategies to address mood and weight concerns in the postpartum period. Thus, this application proposes a randomized controlled trial of a novel, cognitive behavioral postpartum relapse prevention program that addresses women's mood and weight concerns delivered during the postpartum period when the risk of relapse is high. Pregnant women who have quit smoking and are interested in saying quit postpartum (N = 300) will be randomly assigned to: 1) a relapse prevention intervention that addresses mood and weight concerns, or 2) a nondirective, supportive condition designed to control for the effects of therapeutic time and attention. We hypothesize that relapse will be less likely at 6 and 12 months postpartum for women in the intervention group than those in the supportive condition. We will also examine the mediators and moderators of treatment response. Results of this investigation will provide information on the efficacy of a cognitive behavioral relapse prevention intervention that incorporates strategies to address mood and weight concerns to prevent smoking relapse and inform future research on the prevention of smoking and other drug use postpartum.